1. Field of the Invention
The present invention relates to a method for manufacturing a discharge nozzle by which the discharge nozzle in a liquid jet recording head is manufactured by use of sublimation caused by an ultraviolet laser by splashing liquid drops of printing liquid or the like to deposit the liquid drops on a printing medium. The present invention also relates to a method for manufacturing the liquid jet recording head.
2. Related Background Art
For an ink jet printer which splashes drops of ink or the like to deposit them on a printing medium, printing quality largely depends on the characteristics of a nozzle, which ejects recording liquid. Most of these characteristics are determined by nozzle diameter variations and nozzle shape. Methods for forming a nozzle which has thus far been proposed are roughly classified into two types. Methods of one type include electroforming, which uses a metal plate, or electro-discharge, while those of the other type include a method for manufacturing (abrading) an organic macromolecular resin material using sublimation caused by a high-energy laser, such as an ultraviolet laser represented by an excimer laser. An ultraviolet laser method is generally used for fine nozzle manufacturing.
At the time of manufacturing an organic macromolecular material at a laser energy density suited to sublime the material using an ultraviolet laser method, the manufactured area becomes progressively smaller from the side of laser beam incoming to the side of laser beam outgoing, that is, a so-called tapered feature results. Because a nozzle shape required to increase the quality of printing by a liquid jet recording head is tapered to become progressively thinner toward the side of recording liquid ejection, the nozzle is manufactured by emitting a laser beam from the side of recording liquid feed, that is, after the discharge nozzle is manufactured, a plate in which the discharge nozzle is manufactured is jointed to a member which feeds recording liquid.
However, a discharge nozzle is required to be about a few micrometers to about one hundred micrometers long to ensure high printing quality. Moreover, a plate in which discharge nozzles are formed, of course, has the same thickness. A discharge nozzle forming plate is so thin and deformable that the plate must be worked using a laser from the side of liquid feed, and the plate must be jointed to a member which feeds recording liquid. Thus, the discharge nozzle forming plate deforms under stress after it is jointed to the member, so that a plurality of discharge nozzles aligned in the same direction are not formed, resulting in different directions of recording liquid ejection, which in turn deteriorate printing quality.
To solve these problems, methods have been proposed for manufacturing discharge nozzles after assembling a liquid jet recording head.
One of these methods, which is proposed in National Publication of International Patent Application No. 6-510958 (describing an invention by Compaq Computer Corporation), makes light beams, limited using mask patterns, obliquely incident on a discharge nozzle forming plate in two directions. By doing so, the discharge nozzle forming plate is worked in the direction of light beam travel, thus manufacturing discharge nozzles which are tapered so that the tapered form of the manufactured width is wider at inside than outside.
Another method, which is proposed in Japanese Patent Publication No. 6-24874 (Zahl Limited), emits a light beam, with a mask plate on which nozzle patterns are formed in close contact with a discharge nozzle forming plate in such a manner that a light beam is obliquely incident at the mask plate brought into close contact and the discharge nozzle forming plate, and swings or turns the mask plate and the discharge nozzle forming plate on a pivot, so that manufacturing progresses in the direction of light beam incidence, thus manufacturing on the liquid ejection side of the discharge nozzle forming plate discharge nozzles which are tapered so that they are progressively thinner toward their ends.
Because light beam manufacturing is performed in only two directions, the method, described in National Publication of International Patent Application No. 6-510958, forms on the liquid ejection side of a discharge nozzle forming plate in the oblique directions of light beam incidence discharge nozzles which are tapered so that they are progressively thinner toward their ends. In contrast, at right angles to the oblique directions, the method forms on the liquid ejection side discharge nozzles which are tapered so that they fan out toward their ends. Discharge nozzles which are tapered so that they fan out toward their ends are formed on the side of liquid ejection instead of cone-shaped discharge nozzles symmetric about the direction of liquid ejection, thus resisting ejected recording liquid and prolonging a liquid ejection period, so that high-speed printing becomes impossible. What is worse, nozzles fanned out manufacture mist during liquid ejection.
Because as this case does not relate to any projection imaging system, discharge nozzles must be formed one at a time. Thus it takes a long time to manufacture many discharge nozzles. This, in turn, means that the method is disadvantageous in terms of productivity. Because nozzle size sharply varies with the magnitude of light beam energy, it is difficult to keep the tolerance stable.
Because the method described in Japanese Patent Publication No. 6-24874 inclines a mask plate and a discharge nozzle forming plate to a light beam over time, it may be difficult to form tapered discharge nozzles which are symmetric about the direction of liquid ejection, depending on the states at the beginning and end of manufacturing, that is, on the process of manufacturing. As a result, it is difficult to eject recording liquid stably in the same direction from individual liquid jet recording heads.
Although all mask patterns (many arrayed discharge nozzles) can be formed at one time, manufacturing time is limited by inclination time because the method inclines a mask plate and a discharge nozzle forming plate. Thus manufacturing time increases, leading the method to be disadvantageous in terms of productivity.
To solve these problems, the applicant proposed in Japanese Patent Application No. 10-182407 a method which emits a plurality of parallel high-energy ultraviolet beams at the same time in directions at a predetermined angle to a perpendicular to a mask plate and symmetric about an axis, with the mask plate, patterned with the shape of liquid jet recording head discharge nozzles, in close contact with the external surface of a discharge nozzle forming plate, to form in the discharge nozzle forming plate a one-dimensional array of liquid jet recording head discharge nozzles or a plurality of rows of a plurality of arrays of liquid jet recording head discharge nozzles.
A discharge nozzle formed by the method is symmetric about the direction of liquid ejection. The method allows discharge nozzles which are tapered so that they are progressively thinner in part or in whole toward their ends to be formed on the liquid ejection side of the discharge nozzle forming plate. The method also allows many arrayed discharge nozzles to be formed at a time in a short time.
However, to provide a mask plate which is not worked or damaged, that is, exhibits high durability when an ultraviolet beam is emitted with the mask plate in close contact with a discharge nozzle forming plate, it is desired that the level of technology be further enhanced. When a mask plate is brought into close contact with a discharge nozzle forming plate, patterns on the mask plate must be positioned in predetermined locations on the discharge nozzle forming plate. To position patterns in predetermined locations more easily and efficiently, it is also desired that the level of technology be further enhanced.
It is an object of the present invention to provide on the one hand a method for manufacturing discharge nozzles of a liquid jet recording head allows many discharge nozzles, tapered so that they are progressively thinner toward their ends, to be formed on the liquid ejection side of a discharge nozzle forming plate at a time in a short time by emitting a laser beam from the liquid ejection side, wherein a mask plate can be prevented from being damaged and on the other hand a method for manufacturing the liquid jet recording head.
It is another object of the present invention to provide a method for manufacturing discharge nozzles of a liquid jet recording head which brings a mask plate patterned with a shape of a discharge port to be formed, into close contact with a liquid jet side of a discharge port forming plate of the liquid jet recording head and emits a laser beam from the side of the mask plate to fabricate the discharge nozzles on the discharge port forming plate, wherein the mask plate has a quartz substrate and a total-reflection mirror coating layer which is provided in the areas outside the shape of the discharge nozzles on the substrate and the substrate is disposed on the side on which the laser beam is incident.
It is still another object of the present invention to provide a method for manufacturing discharge nozzles of a liquid jet recording head which brings a mask plate patterned with a shape of a discharge port to be formed, into close contact with a liquid ejection side of a discharge port forming plate of the liquid jet recording head and emits an ultraviolet laser beam from the side of the mask plate to fabricate the discharge nozzles on the discharge port forming plate, wherein the mask plate, whose substrate is made of quartz, is given a total-reflection mirror coating matched to the wavelength of the ultraviolet laser beam opposite to the surface of the quartz substrate on which the ultraviolet laser beam is incident and after the total-reflection mirror coating layer is removed according to the shape of the discharge ports, the total-reflection mirror coating layer is overcoated with an inorganic material which transmits ultraviolet rays.
It is a further object of the present invention to provide a method for manufacturing discharge nozzles of a liquid jet recording head which brings a mask plate patterned with a shape of a discharge port to be formed, into close contact with a liquid ejection side of a discharge port forming plate of the liquid jet recording head and emits an ultraviolet laser beam from the side of the mask plate to fabricate the discharge nozzles on the discharge port forming plate, wherein the mask plate, whose substrate is made of quartz, is given a total-reflection mirror coating matched to the wavelength of the ultraviolet laser beam opposite to the surface of the quartz substrate on which the ultraviolet laser beam is incident and after the total-reflection mirror coating layer is overcoated according to the shape of the discharge ports, the total-reflection mirror coating layer and the overcoating layer are removed according to the shape of the discharge nozzles.
According to the present invention, damage to a mask plate can be prevented, and high tolerances are possible because a mask plate does not expand or deform due to heat.
It is a still further object of the present invention to provide on the one hand a method for manufacturing discharge nozzles of a liquid jet recording head which allows a discharge nozzle forming plate and a mask plate to be positioned with respect to each other easily and efficiently and discharge nozzle positioning accuracy to increase when a laser beam is emitted from the liquid ejection side of the discharge nozzle forming plate to form on the liquid ejection side discharge nozzles which are tapered so that they are progressively thinner toward their ends and on the other hand a method for manufacturing the liquid jet recording head.
It is another object of the present invention to provide a method for manufacturing a liquid jet recording head, which brings a mask plate, patterned with the shape of discharge ports to be formed, into close contact with the liquid ejection side of a discharge port forming plate of the liquid jet recording head and emits a laser beam from the side of the mask plate to fabricate discharge nozzles on the discharge port forming plate, wherein the mask plate has a quartz substrate and a total-reflection mirror coating layer which is provided in the areas outside the shape of the discharge ports on the substrate and wherein the substrate is disposed on the side on which the laser beam is incident.
It is another object of the present invention to provide a method for manufacturing a liquid jet recording head which brings a mask plate, patterned with the shape of discharge ports to be formed, into close contact with the liquid ejection side of a discharge port forming plate of the liquid jet recording head and emits an ultraviolet laser beam from the side of the mask plate to fabricate discharge nozzles on the discharge port forming plate, wherein the mask plate, whose substrate is made of quartz, is given a total-reflection mirror coating matched to the wavelength of the ultraviolet laser beam opposite to the surface of the quartz substrate on which the ultraviolet laser beam is incident and wherein after the total-reflection mirror coating layer is removed according to the shape of the discharge ports, the total-reflection mirror coating layer is overcoated with an inorganic material which transmits ultraviolet rays.
It is another object of the present invention to provide a method for manufacturing a liquid jet recording head which brings a mask plate, patterned with the shape of discharge-ports to be formed, into close contact with the liquid ejection side of a discharge port forming plate of the liquid jet recording head and emits an ultraviolet laser beam from the side of the mask plate to fabricate discharge nozzles on the discharge port forming plate, wherein the mask plate, whose substrate is made of quartz, is given a total-reflection mirror coating matched to the wavelength of the ultraviolet laser beam opposite to the surface of the quartz substrate on which the ultraviolet laser beam is incident and wherein after the total-reflection mirror coating layer is overcoated, the total-reflection mirror coating layer and the overcoating layer are removed according to the shape of the discharge ports.
The present invention allows the patterns on a mask plate which is brought into close contact with a discharge port forming plate to be easily and efficiently aligned with each other, thus significantly increasing the accuracy of positioning discharge nozzles.
The present invention also allows many discharge nozzles to be formed at a time in a short time which are symmetric about the direction of liquid ejection and tapered so that they are progressively thinner in part or in whole toward their ends and which have an opening of the same diameter on the liquid ejection side.
The present invention further allows discharge nozzles to be manufactured in the last step after liquid jet recording head assembly, thus preventing ink ejection in different directions which is caused by deformation due to assembly and coupling of a discharge nozzle forming plate. The present invention also allows discharge nozzles which are tapered so that they are progressively thinner toward their ends to be formed on the liquid ejection side of a discharge nozzle forming plate. Thus liquid drop ejection is kept in a direction, and liquid drop ejection speed increases, resulting in significantly enhanced quality of printing by a liquid jet recording head and increased printing speed.